I V I I I A STUDY OF THE RECOVERY OF ALUMINA FROM A CLAY BY GEORGE FERRIS WATSON THESIS FOR THE DEGREE OF BAGHELOROF SCIENCE IN CHEMISTRY COLLEGE OF LIBERAL ARTS AND SCIENCES UNIVERSITY OF' ILLINOIS 1922 5 UNIVERSITY OF ILLINOIS __Augus_t__4___ _I92_3._ THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION BY G eo rge_ F 1 er ris _ Wats on ENTITLED A__Stjudy_ _o f_ _t h_e_ Re cj? verv_ _of_ .Alumina. Fr om_ _Q1 ay IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE degree of _ _ B a c_h elo r _ of _ _S c i_3 no e_ _i n _ C_h e m is t ry X 7 * rt : > Digitized by the Internet Archive in 2015 https://archive.org/details/studyofrecoveryoOOwats I wish to sincerely thank Prof. S. W. Parr and Dr. W. S Putman for the help they have given me on this problem and in preparing this thesis. . . TABLE OF CONTENTS page 1. INTRODUCTION I 2. HISTORICAL 4 3. THEORETICAL 8 4. EXPERIMENTAL II (a) The Sample (b) The Analysis (c) Decomposition by acids and alkali 5. DISCUSSION OF RESULTS 14 6. SUMMARY 16 7. BIBLIOGRAPHY 17 1 . A STUDY OF THE RECOVERY OF ALUMINA FROM A CLAY. I. INTRODUCTION The use of metals in modern times has reached unprecedented heights. Our transportation, buildings, life, prosperity, and civilization directly depend upon its production. The metallurgy of iron has been known and made use of for ages. The ancients were familiar with the uses of brasse and bronzes. But the main demand has fallen upon iron on account of its occurence, known metallurgy, desirable qualities, and many alloys. The oxides of iron compose approximatly five per cent of the earths crust. Thousands of chemists and Technical men have devoted their time to the determination of the properties, metallurgy, alloys and possibilities of the metal. And the problems are ever more com- plex and daily more is discovered as to the characters of the metal and its alloys. It was not until comparatively recent times that the world has been concerned with the rise in importance of a new metal which we know as aluminum. Aluminum occurrs in the ground as a clay or a bauxite in which it is associated with the elements silicon, oxygen, alkali earths, iron, sodium and a few of the common metals. The compounds of aluminum are very important when we realize that they make up eight per cent of the earths crust. Bo that it is very evident that aluminum is every bit as important as iron. At the present time the manufacture of aluminum is dependent upon the supply of the mineral bauxite. This mineral is a com- bination of deaspore (Al.9O3.3H2 ) and brown hematite ( FE 2 0 3 . I . . . ’ . . . . 1 . . . . H 2 3H..0.) In the United States bauxitehas been mined since about 1335, and this supply has been taken from four states, Alabama, Georgia, Tennessee, and Arkansas. 'The following table shows the production of Bauxite by states in the United States Table --I. * Production of bauxite in the United States Alabama)- 27,409 -25, 003 -62, 164 -43, 076 -40,029 Georgia) Tenn. ) -132, 332 -272, 022 -506, 556 -333,490 -431,279. Arkansas ) There were no figures available on the estimated reserves of the supply, but it is safe to conclude that these deposits are cer- tainly only a very small percentage of the total U. S. supply. It is regrettable that a metal of such wide occurence and such valuable properties is obliged to owe its existence to a mineral of such comparatively narrow resources. Also in order for a bauxitic mineral to be of use commercially it must have at least fifty percent of alumina and a low percentage of silica and other impurities. These narrow specifications upon the production of aluminum will in years to come hinder the use of the metal con- si derably . The production of aluminum in commercial quantities given rise to a thousand and one uses. On account of its extreme lightness it has found a ready use in many fields, especially small articles as keyes, vi sting cards, thimbles, cigarette cases, etc. Its use in cooking utensils is known every where on ac- count of its conductivity and resistance to acids. It has been especially valuable in military equipment for its lightness, resistance to oxidation, and strength. Its lightness was also . . • . . - ' . . . . . - . appreciated in the automobile andaeroplane, and a great field was opened up there. And it is now a fact that aluminum more than holds its own with nickle, copper, brass, and even iron. And even with its many uses very little is known concerning its alloying and most economic metallurgy. . 4. 1 1. HI STORY Aluminum is essentially a modern metal. The first reference to such a metal was not until 1760 when Morveau, in Prance, calcined an alum and called the resulting product alumina. Lavoisier first suspected the existence of a metallic base of earths, and he sus- pected alumina of being an oxide of a metal which was called aluminum. The first attempts at the production of pure aluminum was started in 1007, and the general process was the reduction by an alkali metal. Due to the meagre knowledge of electricity and electrical apparatus the decomposition by this method was never studied closely, although Davy did try this method. Wohler was the first to isolate aluminum and he accomplished this by decom- position of aluminum cloride with potassium. But he got a fine gray powder which could not be used for the determination of the properties of the metal. Later in 1845, Wholer got the metalic form by passing potassium va ors over aluminum cloride in boats, ^rom globules obtained here the properties of the metal were de- termined. The main work upon aluminum was left to H. St. Claire Deville, who devoted his life to the study of Aluminum. In 1845 Deville, although ignorant of Wohler's work, passed aluminum cloride over potassium and instead of getting the aluminum proto-clori de he obtained the pure metal. Recognizing the importance of his work the Acd. of Sciences donated two thousand francs for the contin- uance of his work. His first attempts were the decomposition by the use of a battery, but this method was not successful so he turned to the use of sodium as a reducing agent. By this means . - . . . . . I . . . . 5 . a quanity of the metal was prepared, after which Napoleon III. gave him permission to continue his work at the Emperor's expence. By thiB method Deville was given ample funds to pursue his research and he was aided at this time by two young chemists, Chas. and Alex Tissier. These two afterwards left Deville and ipened up plants of their own. Deville operated plants by which aluminum was re- duced by sodium and these plants started in France ran for a num- ber of years and turned out a quanity of the pure metal. From this time on the principle endeavors were chiefly toward perfecting the process and reducing the price of the metal. In 1832 a Company was started in England for the preparation by the usual method and a product of reasonable purity was obtained. At this time came the wonderful invention of H. Y. Castner of New York on tne production of sodium. This invention reduced the price of sodium by seventy five per cent. Mr. Webster of the plant in England induced Mr. Castner to open up a plant in England in which both processes were imployed. This plant was built in 1883 and turned out 100,000 pounds of aluminum annually. The following table gives an indication of the price tend of aluminum. Table II 2 Price of Aluminum 1854 1855 1856 1857 1853 1859 1878 1890 1891 1895 ^/lb. on cont. 259.2 103.50 32.9 25.92 17.33 11.34 2.98 1.30 0.32 The first commercial attempts were about 1885 toward elec- trical decomposition. Of these processes which were patented at that time, those of Cowles, Herault, and Hall stand forth. Chas. k. Hall of Oberlin Ohio prepared a bath of fused cryolite with the al um ina dissolved in it. An electric current was used to precipi- , ' 9 ’ c - . * . 6 . tate the pure aluminum. This process was the wonder of the times as it reduced aluminum to a commercial price with maximum of purity. This process has been the outstanding one wvery since that time and it seems to be the main one for many years to come. The difficult thing now is the preparation of the pure alum- ina. In the early days of aluminum production the preparation of the alumina was tather simple. In a large number of cases the mineral cryolite (AlgS’gSUaF ) was used. Alumina was also prepared by the ignition of ammonium alum or an alum free from iron. Bauxite was also used and alumina prepared by the fusion with sodium car- bonate and formation of sodium alurainate. This alurainate was then extracted with water and filtered. Carbon dioxide was then passed through the clear solution and aluminum hydrate formed. This hyd- rate was then filtered, sodium carbonate regenerated, and the hydrate calcined to alumina. But at the present time alumina is prepared exclusively by the M BAeyer pro cess M . In this process the ore is ground fairly fine, kilned to destroy the organic matter, and mixed with a solution of caustic soda to a sp.gr. of 1.45 at a pressure of seventy pounds per sq. inch for eight hours. The mass is then blown into a tank by its own pressure and water added to a spec. grav. of 1.25 so as not to ruin the asbestos filter which removes the hydrates of iron and silica. The sodium hydrate is agitated with alumina for thirty six hours when approximatly seven- ty per cent of the alumina in the solution will be precipitated. The Alumina is then filtered, washed, and partially dried. The filtarte is then concentrated to 1.45 and used for another batch of solution. The precipitate is finally calcined at 1000 degrees to insure proper crystalline form. . . . ■ * . 7 The mystery, romance and financial promise of aluminum have attrached chemists and technical men from all the world. Enorm- ous amounts of work have been done upon the manufacture of the metal. But it is readily seen that the amount of work yet to be done is stupendous. The results of these men are shown in the numerous patents in the Capitals of the various nations. But these processes have not brought forth any startling advances. The various methods for the purification of the alumina all follow the same principles; a reduction with an alkali or an alkali earth; a replacement by an active gas as a halogen or carbon dioxide; or a pure solution with a strong solvent. * . > 3 . Ill THEORETICAL The preparation of alumina for the manufacture of aluminum must be a true commercial and economic process. The old time processes of fusion with sodium carbonate or ignition of an alum can not be considered for several reasons. Pirst is the limited supply of the mineral with which they are concerned; second the obious cost of materials and the waste which they produce. At the present time we are preparing alumina by the Baeyer process which I have previously describe in the Historical section. This is a good method an economical one if we have a large supply of the proper mineral to work with. In order for this process to be commercial the alumina content must be above fifty per cent, the Siog content below 15 percent, and the Fe£03 and Sio2 con ‘t® n 't correspondingly low. How this imposes narrow specifications upon the use of this process as today only certain bauxites are used. It is necessary that this process be improved, a larger supply of the mineral opened up, or a new process developed. In looking up the literature upon this subject we are surprised with the scores of patents issued for the manufacture and purification of alumina. But when we study these we find that they all simmer down to really a few which hold the gen- eral principles for them all. So we will here mention a few showing what is being done in the line of new processes. We find a number of the new processes depending upon the solvent action of some acid or alkali. United States Patent I, 301,394 was issued for the decomposition of aluminous ores with sulphuric acid. The aluminum dissolved was converted into the alum by the addition of potassium sulphate. Then the alumina was . - . . . , . . , ' ; * prepared by ignition and the K 2 SO 4 was regenerated. How this pro- cess makes it necessary that the aluminum material present be sol- f uble in sulphuric acid. And it is a fact that only a small por- tion of our aluminous ores have the aluminum held in a sulphuric acid soluble condition. Reduction processes have been rather popular since the discovery of aluminum. Mr. H. A. Richmond has developed a process along these lines. This process consisted in mixing kaolin, pyrites, and carbon in the proportions of 132,120,21. This mixture was heated in an electric furnace to a high temperature where the alumina formed as a molten layer on top of the molten iron. Carbon monoxide and SiS 2 are given off as a gas. Where sulphur is used instead of the pyrites the alumina was practically pure. The process is valuable as it takes care of the iron present in the ore which is always a very troublesome element. This process seems to be of considerable value especially when the time comes for the removal of aluminum from blast furnace slags. A process very similar to the "Baeyer Process" was developed by B. J. Halvorsen and issued in U. S. patent I, 333, 020. ® This consisted in treating labradorite with ammonia in an auto clave at a pressure of from ten to fifteen atmospheres, for eight hours. This is then removed by decatation and filtration and heated to 150 degress. Thus the alumina is formed, the ammonia is regenerated Louis-Gabriel Patrouilleau worked upon a silica aluminous ore which was very nearly free from iron. He heated the ore to a dark residue and then passed clorine gas thru it. This gave the j clo rides of silica and aluminum. The Si cl 4 was decomposed with water and the H 2 Si 04 was separated. The hydro clo ric acid was . . ' 1 - . . . . 10 . expelled upon evaporation. Thio process has the obvious diffi- culty that it must be free from iron when in reality it is very hard to obtain an aluminous ore which does not contain more or less iron. An unusual process is that of E. E. Dutt in which ASgOg is used instead of the So2« Olay is acted upon at a red heat by the oxide in the presence of calcium cloride. The calcium aluminate formed is treated with aluminum cloride and water and the result ing product is the aluminum hydroxide. This aluminum hydroxide is then calcined to alumina. This process seems to have some promise to it but for economical reasons it would probably run into difficulties. So that in examining a clay or a mineral as to its poss- ibilities in the aluminum industry there are no precedents to follow. Each investigar has a problem of his own depending upon the ore used. > : '■ . K y ■ . . . . . 11 . IV EXPERIMENTAL The samples of the material used in this work were obtained from Dr. Parmelee 8 of the Dept, of Ceramics of the University of Illinois. The samples were obtained by that department from de- posits in the state of Missouri which are situated along the C. R. I. & P. railroad in the counties of Pranklin, Gasconade, and Maries. These deposits have been worked fro some time and. the product used for the manufacture of abrasives and of refractories. There were no figures available as to the possible extent of the deposits but they have long been looked upon as a possibility in the manufacture of aluminum. The clay is a rough, sandy looking material with a yellowish or somewhat reddy appearance. The clay is of a diaspore composition. The analysis of this material was made by a sodium carbonate fusion in a platinum crucible. By this means everything went into solution. The fusion was carried out in the ordinary way and re- sulting material was dissolved in HLC and evaporated to dryness. It was then taken up with water and again evaporated to dryness. The residue was taken up with water and the J^SiC^ had impurities of aluminum hydroxide so the silica was dissolved in HP and the residue ignited and weighed. This loss in weight gave the correct amount of silica in the sample. The aluminum present in the sam- ple was precipitated with NH^OH and NH^Cl, filtered, ignited and weighed. The Pe present in the aluminum was dissolved out with HCh and Lc titrated with standard Kuno^. The loss in weight of the aluminum gave the correct amount of aluminum present. The calcium and barium were precipitated from the aluminum hydroxude filtrate by (NH 4 )2 c 2°4 and filtered ignited and weighed. The following table _gj .v_eB t h e,.„analyji.^-. * . . . . . . . . Table III 12 Analysis of Missouri Olay Moisture — 0.33$ Si0 2 — — 11.70 $ Alumina Calcium (CaO) Fe 2°3 80 • 80$ 5.2 I . 35$ total 99.98 This analysis was also made by Dr. W. S. Cox 9 in which he found the analysis to bei- Table IV Analysis of Missouri Clay (By Dr. W. S. Cox) Moisture 0.60$ Wat er 14.00$ Si0 2 9.30 $ a1 2°2 -73.73$ Fe 2°S 0.57$ Na g o 2.00$ k 2 o — — 0.52$ The clay was then attacked as to its stability to acids and alkalis. A sample was treated in a casserole with the solvent for two days. This was taken to dryness if possible but in the case of sulphuric acid the final step was then heating to dryness with a flame. The residue was taken up in water and filtered and ignited to dryness and weighed. This gave the amount of material which had been decomposed by the solvent. The water soluble portion was then neutralized and made slightly acidic. MH oh and 1TH OH were added to . . 13. excess and the aluminum hudroxide was filtered off, ignited and weighed. This gave the amount of aluminum which the solvent had dissolved from the sample. This proceedure was followed out with the solvents H 2 S0 4 (cone.), H 2 SQ 4 (dil.), Aqua Regia, NaOh (10 N. ) and KOH (10). Table V Decomposition of clay by acids and alkali 20 . 4 c /o 13.5 # 16.5 # 22.7 # 20.90 # With H o S0/ (cone.) " K 2 S0 4 (dil. ) M Aqua Regia M NAOH (10 N.) " KOH (ION.) The amount of alumina which was dissolved from the sample was calculated on the assumption that there was no Iron present. Table VI Per Cent of Alumina Dissolved from Sample With H 2 S0 4 (cone.) 20.4# " H 2 S0 4 ( dil.) 13.5# H Aqua Regia 4.54# NaOH (10 N.) KOH ( 10 N.) Alumina per cent of total Alumina Content With H 2 S0 4 (conc.) — 25.2# " H 2 S0 4 (dil.) — -16.7 # '• Aqua Regia — ~ 5.12# " NaOh (10 N.) —28.1 # KOH (ION.)) —.25.$# ——22.7 # 20.90# ii V. DISCUSSION OF RESULTS 14 The aluminous material which is obtained from the counties of Franklinn, Gasconade, and Maries in the State of Missouri has no commercial value for the manufacture of alumina by chemical solvent ;i without the aid of high pressure and high temperature. In order for a mineral to be such it should give up at least fifty per cent i of its alumina to a fairly cheap solvent which might be regenerated, and used continously. In the examination of this material I have used the beet and strongest solvents which we have knowledge of, and in no case have satisfactory results been obtained. I find that it was impossible to dissolve more than twenty two per cent of the mineral or was it possible to change more than twenty five per cent of the alumina present into a soluble form. This was sufficient evidence to show that the aluminum was present in the mineral as a silicate or other insoluble form. And this would render that mineral unsuitable for working with chemicals. But the value of this ore as an aluminous material does not necessarily lie in its susceptability to solvents. At the pre- sent time the aluminum industry has in use processes which are truly economic ones. They make several requirements which the mineral must fulfill before it can be of use. That is they re- quire that the alumina content must be high, the silica content must be low, the iron and titanium contents must also be low. These requirements have so far been fulfilled only by bauxite. But here we have an ore which is rich in alumina, which is low in silica, and which has practically no iron and no titanium. This mineral meets the requirements in all respects and should be of value in respect to the "Baeyer Process”. This process uses a . . . . . * * 15 . a high pressure and heat to break down those bonds which hold the aluminum in the mineral. And that is obviously the only method of attack sonce is so inert to the action of our common solvents. . 16 . VI. SUMMARY OF RESULTS I. The analysis of the clay given. II. The Analysis agrees with that of other investigators. 5. The alumina content was shown to be higher than was supposed. 4. The stability of the mineral to acids and alkalis was shown. 5. The amount of the alumina present which w as susceptible to common solvents was shown. 6. The aluminum was shown to be present as the silicate rather than the aluminate. 7. The clay was shown to be undesirable for easy chemical decomposition. 8. It was shown that the clay was in all probability desirable when applied to such a process as the "Baeyer Process." . . . . 17 VII BIBLIOGRAPHY 1. G. A. Roush, Mineral Industry, 29* 7 (1920) 2. Minet The Production of Aluminum (1905) 3. Oliver, R. S, U. S. Patent 1,301, 394 Laist, P. Chern. Abstr. 13 1907 (1919) Freiche, F. F. 4. Richmond, H. A. U. S. Patent 1,245,383 Chem. Abstr. 12 253 (1918) 5. Halvorsen, B. F. U. S. Patent 1,333, 020 Chem. Abstr. 4__ 1416 (1920) 6. Patrouilleau, L. G. Fr. Patent 481, 106 Chem. Abstr. 12 1337 (1918) 7. Dutt, E.E. . U. S. Patent 1,332, 115 Chem. Abstr. 14 1194 (1920) 8. Parmelee, Cer tidies Department, Univ . Illinois 9. Cox, ¥. S. Am. Mineralogist 2 144 (1917) 3 154 (1918)